Bone-block iliotibial-band transfer for anterior cruciate insufficiency

Anatomic anterior cruciate ligament reconstruction: Freddie Fu's paradigm

Anterior cruciate ligament (ACL) reconstruction techniques have evolved over the past four decades. There is evidence that non-anatomic reconstruction techniques, such as traditional transtibial drilling, fail to recreate the native anatomy of the ACL, which can lead to increased rotatory knee instability, revision risk, and post-traumatic osteoarthritis. Anatomic ACL reconstruction has emerged as the gold standard, with the goal of restoring the patient's native anatomy and knee kinematics. This review will summarise the relevant anatomy, modern anatomic ACL reconstruction techniques, and literature supporting anatomic ACL reconstruction as the new paradigm. LEVEL OF EVIDENCE: Level V, review article.

Rehabilitation And Advances In Surgical Reconstruction For Anterior Cruciate Ligament Insufficiency: What Has Changed Since The 1960s? - State Of The Art

Anterior cruciate ligament (ACL) insufficiency can be disabling, given the physical and sports activity constraints that negatively impact the quality of life. Consequently, surgery is the main approach for most active patients. Nonetheless, ACL reconstruction (ACLR) cannot be successful without adequate preoperative and postoperative rehabilitation. Since the 1960s, post-ACLR rehabilitation has evolved, mainly from advances in surgery, coupled with a better understanding of the biological concepts of graft revascularization, maturation and integration, which have impacted ACL postoperative rehabilitation protocols. However, new technologies do involve a definite learning curve which could affect rehabilitation programs and produce inconsistent results. The development of rehabilitation protocols cannot be defined without an accurate diagnosis of ACL injury and considering the patient's main physical demands and expectations. This article discusses how postoperative rehabilitation following ACLR has changed from the 1960s to now, focussing on surgical technique (type of tendon graft, fixation devices, and graft tensioning), biological concepts (graft maturation and integration), rehabilitation protocols (prevention of ACL injuries, preoperative rehabilitation, postoperative rehabilitation), criteria to return to sports, patient's reported outcomes and outcome. Although rehabilitation plays an essential role in managing ACL injuries, it cannot be fully standardised preoperatively or postoperatively. Preoperative and postoperative rehabilitation should be based on an accurate clinical diagnosis, patients' understanding of their injury, graft tissue biology and biomechanics, surgical technique, the patient's physical demands and expectations, geographical differences in ACL rehabilitation and future perspectives.

Single-Tunnel Double-Bundle-Like Effect With Footprint Enhancing Anterior Cruciate Ligament Reconstruction

The anterior cruciate ligament (ACL) consists of an anteromedial bundle and a posterolateral bundle giving anteroposterior and rotational stability. It's one of the most commonly injured ligaments and also one of the most commonly performed arthroscopic procedures. Management of ACL injuries is one of the most frequently studied subjects in the literature. Surgical management of ACL injuries varies from extraarticular tenodesis to arthroscopic transtibial reconstruction to double-bundle reconstruction to anatomic single-bundle reconstruction. Although double-bundle ACL reconstruction gives more rotational stability than anatomic single-bundle, functional outcome of both are the same, but the complication rates are much higher for double-bundle reconstruction. Hence, anatomic single-bundle ACL reconstruction has gained popularity. The femoral and tibial footprint of the ACL varies in shape and size; it can be oval, elliptical, rectangular, C-shape, and more. But all available ACL reconstruction techniques prepare a circular tunnel; hence, the footprint coverage of the native ACL is maximum after double-bundle reconstruction and less after anatomic single-bundle reconstruction. So, to have the benefit of double-bundle reconstruction with a single tunnel, we propose our technique of a single-tunnel double-bundle-like effect, with the footprint enhancing ACL reconstruction using our newly designed tunnel dilators.

In-out versus out-in technique for ACL reconstruction: a prospective clinical and radiological comparison

Background

Several studies have recently shown better restoration of normal knee kinematics and improvement of rotator knee stability after reconstruction with higher femoral tunnel obliquity. The aim of this study is to evaluate tunnel obliquity, length, and posterior wall blowout in single-bundle anterior cruciate ligament (ACL) reconstruction, comparing the transtibial (TT) technique and the out–in (OI) technique.

Materials and methods

Forty consecutive patients operated on for ACL reconstruction with hamstrings were randomly divided into two groups: group A underwent a TT technique, while group B underwent an OI technique. At mean follow-up of 10 months, clinical results and obliquity, length, and posterior wall blowout of femoral tunnels in sagittal and coronal planes using computed tomography (CT) scan were assessed.

Results

In sagittal plane, femoral tunnel obliquity was 38.6 ± 10.2° in group A and 36.6 ± 11.8° in group B (p = 0.63). In coronal plane, femoral tunnel obliquity was 57.8 ± 5.8° in group A and 35.8 ± 8.2° in group B (p = 0.009). Mean tunnel length was 40.3 ± 1.2 mm in group A and 32.9 ± 2.3 mm in group B (p = 0.01). No cases of posterior wall compromise were observed in any patient of either group. Clinical results were not significantly different between the two groups.

Conclusions

The OI technique provides greater obliquity of the femoral tunnel in coronal plane, along with satisfactory length of the tunnel and lack of posterior wall compromise.

Level of evidence

II, prospective study.

The evolution of ACL reconstruction over the last fifty years

Anterior cruciate ligament (ACL) reconstruction has evolved considerably over the past 30 years. This has largely been due to a better understanding of ACL anatomy and in particular a precise description of the femoral and tibial insertions of its two bundles. In the 1980s, the gold standard was anteromedial bundle reconstruction using the middle third of the patellar ligament. Insufficient control of rotational laxity led to the development of double bundle ACL reconstruction. This concept, combined with a growing interest in preservation of the ACL remnant, led in turn to selective reconstruction in partial tears, and more recently to biological reconstruction with ACL remnant conservation. Current ACL reconstruction techniques are not uniform, depending on precise analysis of the type of lesion and the aspect of the ACL remnant in the intercondylar notch.

The story of anterior cruciate ligament reconstruction--Part 1

Once upon a time the anterior cruciate ligament (ACL) enjoyed a relatively unchartered existence, when only a fall from a jousting horse or chariot might have sent a knight or gladiator into early retirement due to an unstable knee. In today's world of high speed travel and an ever increasing number of sports enthusiasts, injuries of the ACL are almost common place with a yearly incidence of about 35 per 100,000 of the population. Although we have known about the existence of the cruciate ligaments since they were first described by Galen over 2000 years ago, awareness of their function and the consequences of their loss were not appreciated until much later. Robert Adams observed the first clinical case of an ACL tear in 1837 but treatment in those days was largely conservative and surgery was reserved for life threatening conditions as mortality was high. The first ACL repair was performed in 1895 by Mayo-Robson of Leeds and was followed by Grekow and Hey Groves who initiated ACL reconstruction with autologous tissue between 1914 and 1920, almost as we know it today.

Lyophilised medial meniscus transplantations in ACL-deficient knees: a 19-year follow-up

PURPOSE

The treatment of meniscal tears has changed since the early 1980s. Meniscus transplantation emerged as a treatment option during that period. This study aims to present the long-term results of the first lyophilised meniscus allograft transplants in Turkey.

METHODS

Between 1990 and 1992, four transplants of the medial meniscus combined with anterior cruciate ligament (ACL) reconstruction were performed on patients with a history of medial meniscectomy and anterior knee instability at our institution. For all patients who underwent meniscus lyophilised allograft transplantation and revision ACL reconstruction, clinical outcomes were evaluated over a mean period of 19 years of postoperative follow-up by clinical assessment, Tegner score, Lysholm score, Knee Society Score, radiography and magnetic resonance imaging (MRI).

RESULTS

The median value of Tegner score was 3 before index surgery and 2.5 at year 19 postoperatively. The median value of Lysholm score was 60.5 before index surgery and 62.5 at year 19. All of the patients had Outerbridge grade IV osteoarthritis by X-ray examination at year 19.

CONCLUSION

Successful meniscus transplantation depends on many factors. This study examines the effect of allografts on these factors and describes experiences with lyophilised allografts in four male patients.

LEVEL OF EVIDENCE

IV.

[Congenital dislocation of the knee (CDK)]

Congenital dislocation of the knee (CDK) is a rare deformity presenting itself either as an isolated idiopathic entity or in the context of syndromes like arthrogryposis, myelodysplasia or Larsen syndrome. Patients can be diagnosed clinically after childbirth based on hyperextension of the knee. Confirmation of the diagnosis is done by X-ray or sonography. Many theories concerning the pathogenesis have been proposed since CDK was described; according to recent literature fibrosis and contracture of the m. quadriceps is the most likely reason. Therapy should start as soon as possible after birth, conservatively using redressing casts or operatively in syndromal conditions aiming for reduction. The prognosis concerning re-dislocation is benign; a good outcome was shown for idiopathic CDK.

Surgery for anterior cruciate ligament deficiency: a historical perspective

The anterior cruciate ligament (ACL) has entertained scientific minds since the Weber brothers provided biomechanical insight into the importance of the ACL in maintaining normal knee kinematics. Robert Adams described the first clinical case of ACL rupture in 1837 some 175 years to date, followed by Mayo-Robson of Leeds who performed the first ACL repair in 1895. At that time, most patients presented late and clinicians started to appreciate signs and symptoms and disabilities associated with such injuries. Hey Groves of Bristol provided the initial description of an ACL reconstruction with autologous tissue graft in 1917, almost as we know it today. His knowledge and achievements were, however, not uniformly appreciated during his life time. What followed was a period of startling ingenuity which created an amazing variety of different surgical procedures often based more on surgical fashion and the absence of a satisfactory alternative than any indication that continued refinements were leading to improved results. It is hence not surprising that real inventors were forgotten, good ideas discarded and untried surgical methods adopted with uncritical enthusiasm only to be set aside without further explanation. Over the past 100 years, surgeons have experimented with a variety of different graft sources including xenograft, and allografts, whilst autologous tissue has remained the most popular choice. Synthetic graft materials enjoyed temporary popularity in the 1980 and 1990s, in the misguided belief that artificial ligaments may be more durable and better equipped to withstand stresses and strains. Until the 1970s, ACL reconstructions were considered formidable procedures, often so complex and fraught with peril that they remained reserved for a chosen few, never gaining the level of popularity they are enjoying today. The increasing familiarity with arthroscopy, popularised through Jackson and Dandy, and enhancements in surgical technology firmly established ACL reconstruction as a common procedure within the realm of most surgeons' ability. More recently, the principle of anatomic ACL reconstruction, aiming at the functional restoration of native ACL dimensions and insertion sites, has been introduced, superseding the somewhat ill-advised concept of isometric graft placement. Double-bundle reconstruction is gaining in popularity, and combined extra- and intra-articular procedures are seeing a revival, but more accurate and reliable pre- and post-operative assessment tools are required to provide customised treatment options and appropriate evaluation and comparability of long-term results. Modern ACL surgery is united in the common goal of re-establishing joint homoeostasis with normal knee kinematics and function which may ultimately assist in reducing the prevalence of post-operative joint degeneration. This review hopes to provide an insight into the historical developments of ACL surgery and the various controversies surrounding its progress. Level of evidence V.

Management of anterior cruciate ligament rupture in patients aged 40 years and older

The aim of anterior cruciate ligament (ACL) reconstruction is essentially to restore functional stability of the knee and to allow patients to return to their desired work and activities. While in the young and active population, surgery is often the best therapeutic option after an ACL tear, ACL reconstruction in middle-aged people is rather more controversial due to concerns about a higher complication rate. The purpose of our article is to establish, through a systematic review of the literature, useful decision-making criteria for the management of anterior cruciate ligament rupture in patients aged 40 years and older, guiding surgeons to the most appropriate therapeutic approach. Various reports have shown excellent results of ACL reconstruction in patients over the age of 40 in terms of subjective satisfaction, return to previous activity level, and reduced complication and failure rates. Some even document excellent outcomes in subjects of 50 years and older. Although there are limited high-level studies, data reported in the literature suggest that ACL reconstruction can be successful in appropriately selected, motivated older patients with symptomatic knee instability who want to return to participating in highly demanding sport and recreational activities. Deciding factors are based on occupation, sex, activity level of the subject, amount of time spent performing such highly demanding activities, and presence of associated knee lesions. Physiological age and activity level are more important than chronological age as deciding factors when considering ACL reconstruction.

Current knowledge in the anatomy of the human anterior cruciate ligament

The anterior cruciate ligament (ACL) is one of the most frequently studied structures of the musculoskeletal system and continues to stimulate debate and challenges among researchers and surgeons. The ultimate goal of anatomic reconstruction surgery is to restore the native anatomy as much as possible. However, this requires thorough knowledge of its anatomy. The aim of this article is to review the current knowledge of the anatomy of ACL along with its macrostructural and ultrastructural properties.

Synthetic grafts for anterior cruciate ligament rupture: 19-year outcome study

Artificial ligaments for ACL replacement have been widely used in the 1980s and early 1990s in orthopaedic surgery. Synthetic devices have been utilized either as a prosthetic material or as an augmentation for a biological ACL graft substitute. The initial enthusiasm surrounding the introduction of synthetic graft materials stemmed from their lack of donor morbidity, their abundant supply and significant strength of these devices. The disadvantages in long-term follow-up were found to be cross-infections, immunological responses, tunnels osteolysis, femural and tibial fractures, foreign-body synovitis and knee osteoarthritis. A total of 126 patients were treated with artificial ACL substitution with polyethylene terephthalate (PET) synthetic ligaments in our Institute between 1986 and 1990. Of the original group, 51 sportsmen aged 15 to 40 were followed-up at a mean of 19years (range 17.5 to 20.6years) after surgery. Assessment was made with KOOS and IKDC score, Tegner activity scale, clinical examination, KT-1000 arthrometer, and X-ray evaluation. Of the 51 patients followed-up, 27.5% were found to have ruptured their PET ligaments and 100% presented degenerative osteoarthritis at the X-ray evaluation according to Ahlbäck radiological classification of arthritis. The objective evaluation showed functional impairment in 29.4% with an average reduction of 3 points in the Tegner activity scale. The osteoarthritis observed in all patients prompted us to avoid the diffusion of this surgical technique. Although in theory well-conceived, studies have yet to substantiate the function of these augmentation devices or to show clinical better results than those achieved with isolated autograft or allograft ACL substitutes.

Anterior cruciate ligament reconstruction with synthetic grafts. A review of literature

Anterior cruciate ligament (ACL) rupture, one of the most common knee injuries in sports, results in anteroposterior laxity, which often leads to an unstable knee. Traditional ACL reconstruction is performed with autograft; disadvantages of this technique are donor site morbidity and a long rehabilitation period. In the 1980s, artificial ligaments became an attractive alternative to biological grafts. The initial enthusiasm surrounding their introduction stemmed from their lack of donor morbidity, their abundant supply and significant strength, immediate loading and reduced postoperative rehabilitation. Synthetic grafts made of different materials such as carbon fibers, polypropylene, Dacron and polyester have been utilised either as a prosthesis or as an augmentation for a biological ACL graft substitute. Nevertheless, every material presented serious drawbacks: cross-infections, immunological responses, breakage, debris dispersion leading to synovitis, chronic effusions, recurrent instability and knee osteoarthritis. Recently, a resurgence of interest in the use of synthetic prostheses has occurred and studies regarding new artificial grafts have been reported. Although many experimental studies have been made and much effort has been put forth, currently no ideal prosthesis mimicking natural human tissue has been found.

Primary arthroplasty is better than internal fixation of displaced femoral neck fractures: a meta-analysis of 14 randomized studies with 2,289 patients

BACKGROUND

The treatment of displaced femoral neck fractures has long been debated. 14 randomized controlled studies (RCTs) comparing internal fixation with primary arthroplasty may give material for evidence-based decision making.

METHODS

Computerized databases were searched for RCTs published between 1966 and 2004. 14 RCTs containing 2,289 patients were included in a metaanalysis regarding complications, reoperations and mortality. The analysis was performed with software from the Cochrane collaboration.

RESULTS

Primary arthroplasty leads to significantly fewer major method-related hip complications and reoperations, compared to internal fixation. There was no significant difference in mortality between the two groups at 30 days and 1 year. Most of the studies found better function and less pain after primary arthroplasty.

INTERPRETATION

Primary arthroplasty should be used in most patients with displaced femoral neck fracture. The healthy, lucid individual, 70-80 years old, should be given a total hip arthroplasty. The older, impaired or institutionalized patient would benefit from a hemiarthroplasty.

Postoperative evaluation of femoral tunnel position in ACL reconstruction: plain radiography versus computed tomography

Inaccurate femoral tunnel placement has been identified as one of the most frequent errors in failed anterior cruciate ligament reconstructions. Most surgeons evaluate the femoral tunnel position on plain radiographs but in a lot of cases it is difficult to detect the femoral tunnel. The goal of this study was to compare plain digital radiographs and multiplanar computed tomography (CT) scans for the evaluation of femoral tunnel position. We examined 50 patients 24-60 months postoperatively, following an arthroscopically-assisted anterior cruciate ligament reconstruction with central third bone-patellar tendon-bone graft. Endobutton fixation was used on the femoral side and titanium interference screws on the tibial side. Standard antero-posterior and lateral X-rays and a CT scan were obtained from each patient. Sagittal and frontal reconstructions of the CT scan were used for the evaluation. We measured the height of the center of the tunnel in the notch in the frontal plane, and the position of the tunnel along Blumensaat's line (BL) in the lateral plane. Measurements are reported as percentages of total notch height and of the length of BL. On plain X-rays the tunnel was invisible in 46 cases in the anterior-posterior plane and in eight cases on the lateral plane. The average position in the frontal plane was 89.8%, and in the lateral plane 38.6%. In the CT scans, measurements were able to be done in 48 patients. The frontal-plane position averaged 90.5% and the lateral-plane position 34.1%. Pearson's correlation coefficient for the values in the lateral plane for CT and X-rays was low at 0.22, with p>0.05. In our group of 50 patients we were able to detect the femoral tunnel on both plains of standard X-rays in only four patients, whereas it was possible to take accurate measurements in 48 patients on reconstructed CT scans. We advocate the use of CT technology for the evaluation of femoral position whenever precise measurements are needed.

Avaliação biomecânica dos tendões dos músculos tibiais e proposta de sua utilização como aloenxertos nas reconstruções do ligamento cruzado anterior

Com o objetivo de avaliar as propriedades mecânicas dos tendões dos músculos tibial anterior (TA) e tibial posterior (TP), o autor realizou ensaios mecânicos com tendões extraídos de 18 cadáveres humanos frescos, do sexo masculino, com média de idade de 45,2 ± 10,7 anos. Os tendões foram divididos em dois grupos e armazenados a -20°C e a -86°C durante 30 a 90 dias antes dos testes. Depois de descongelados, foram feitas medidas da área de secção transversa dos tendões e ensaios mecânicos de tração até a ruptura a uma velocidade de aplicação de carga de 20 mm/min. Foram determinadas as seguintes propriedades biomecânicas: resistência máxima, coeficiente de rigidez, módulo de elasticidade e alongamento máximo relativo; os dados obtidos foram comparados aos existentes na literatura relativos ao ligamento cruzado anterior (LCA) e seus substitutos mais utilizados. A comparação dos dados obtidos neste estudo com os estudos biomecânicos feitos por outros autores nos permitiu observar que o TA e o TP apresentam propriedades mecânicas que os tornam possíveis substitutos do LCA nos casos em que a necessidade de enxertos alógenos se impuser.

A survey of the tension applied to a doubled hamstring tendon graft for reconstruction of the anterior cruciate ligament

PURPOSE

Currently there is no consensus regarding the amount of tension to apply to a graft when reconstructing the anterior cruciate ligament (ACL). We undertook a study to determine whether sports trained orthopedic surgeons tension hamstring tendon grafts maximally during ACL reconstruction, and also whether surgeons tend to load their grafts within a narrow range of tensions.

TYPE OF STUDY

Cross-sectional study.

METHODS

One fresh-frozen cadaveric knee with appropriately placed femoral and tibial tunnels and five pairs of preconditioned semitendinosus and gracilis tendons were used. Custom-made computer software and a custom-made, load measurement device was employed. Thirteen orthopedic sports medicine physicians from our community took part in the study. Surgeons were asked to tension the graft as they would in surgery and were then asked to tension the graft maximally.

RESULTS

The mean and standard deviation of the normal tension (14.8 +/- 7.2 lb) was significantly less (P =.005) than the mean maximal tension (22.3 +/- 6.9 lb).

CONCLUSIONS

This study shows that most ACL surgeons do not tension their graft maximally. Moreover, graft tensioning is highly variable among sports medicine orthopedists. These findings revisit the question as to whether tension should be more accurately measured and controlled for intraoperatively.

The Insall legacy in total knee arthroplasty

John N. Insall was a pioneer in the field of knee surgery. He was a rare individual who accomplished unparalleled levels of success as a surgeon, designer, and teacher. During the past 4 decades, he was instrumental in evolving total knee arthroplasty to its current state of excellence. Insall's impact on orthopaedics is felt by all who have come in contact with him.

The ligament augmentation device: an historical perspective

Anterior cruciate ligament (ACL) injury is the most common ligament injury in the knee, and a significant number of patients may develop progressive instability and disability despite aggressive rehabilitation. Various materials have been used for its reconstruction. These include autografts, allografts, prosthetic ligaments, and synthetic augmentation of the biological tissue. The concept of ligament augmentation device (LAD) arose from the observation that biological grafts undergo a phase of degeneration and loss of strength before being incorporated. The LAD is meant to protect the biological graft during this vulnerable phase. However, it provokes an inflammatory reaction in the knee, and has been found to delay maturation of autogenous graft in humans. In experimental situations, the LAD has been found to share loads in a composite graft. It has also been found to be substantially stronger than the biological graft. However, in clinical situations no significant advantages have been observed with the use of LAD to augment patellar tendon or hamstring reconstruction of the chronic ACL-deficient knee or in the acute setting to augment repair of the torn ACL. There are very few reports of the use of LAD in reconstruction of the posterior cruciate ligament, and again these do not suggest any advantage in its use. Insertion of the LAD implies the introduction of a foreign material into the knee, has been associated with complications such as reactive synovitis and effusions, and may also be associated with an increased risk of infection. At present, there is no evidence that its routine use should be advocated in uncomplicated reconstructions of the ACL using biological grafts.

Anterior cruciate ligament reconstruction and joint dynamics during stair climbing

Athletes with anterior cruciate ligament (ACL) deficiencies exert decreased knee extension moments during level walking (quadriceps avoidance gait), and yet within a few months of ACL reconstruction they are often expected to return to competitive sport. To investigate this issue further, 10 normal subjects and seven ACL deficient patients were evaluated both pre- and post-operatively (mean follow-up of 6 months), and each performed multiple trials ascending a staircase which consisted of three steps. Bilateral joint angles, moments, powers, and work were measured and the data were ensemble averaged and statistically analyzed (repeated measures ANOVA with significance level set at 0.05). Anterior-posterior knee laxity decreased significantly (from 7.9 mm to 5.8 mm) while subjective knee function also improved following ACL reconstruction (knee score increased from 70.4 to 88.5). Pre-operatively, there were no statistically significant differences in biomechanical parameters between the patients' ACL-deficient and intact sides and the normal subjects. Post-operatively, however, statistically significant reductions were seen for the peak moment (91.9 vs 22.5 Nm), power (181 vs 84 W), and work performed (28.0 vs -5.6 J) at the injured knee, which was also the knee from which the patellar tendon graft had been harvested. These reductions were accommodated by significant increases in excursion, moment, and power at the contralateral ankle joint. The results indicate that while the ACL reconstruction were successful in restoring anterior-posterior knee stability, the decrease in knee power and work performed post-operatively by the injured (i.e., donor) knee suggests that donor site morbidity may need to be critically evaluated over a long-term period.

A prospective outcome study of rehabilitation programs and anterior cruciate ligament reconstruction

We evaluated the outcome of and compared two rehabilitation programs (clinic-based versus home) after a mid-third patellar autograft reconstruction of the anterior cruciate ligament. Thirty-seven patients (28 male, 9 female; average age, 24.1 years) completed the study. Fifteen of these patients received clinic-based rehabilitation (three visits per week for 6 weeks prescribed), and 22 patients received home-based physical therapy (number of visits determined by patient response). Knee ROM, Lysholm, Visual Analogy Scale, (VAS) pain rating, hop test, KT-1000, and Sickness Impact Profile (SIP) were evaluated preoperatively and postoperatively. All patients reported good satisfaction with the function of their knee at average follow-up of 21.6 months (range, 12 to 48). Patients managed by home rehabilitation averaged 2.85 visits as compared with 14.2 for clinic-centered patient (P < .05). There were no differences in functional or subjective outcomes in the different postoperative rehabilitation regimens, with both groups reporting high satisfaction and improved quality of life. Cost savings in the home rehabilitation group were significant.

A prospective, clinical study evaluating arthroscopic ACL reconstruction using the semitendinosus and iliotibial band: 2- to 5-year follow up

Seventy-three ACL-deficient knees were reconstructed using a modified Zarins and Rowe arthroscopic procedure utilizing the semitendinosus tendon and iliotibial band (ITB). Fifty of 73 patients returned for 2- to 5-year follow up. On follow-up visit each patient completed a questionnaire pertaining to subjective results, including level of pain and return to, activities. Physical examination included the Lachman test, anterior drawer, pivot shift, and anterior subluxation tests (using the Stryker KT 1000), each graded 0 to 3. All patients have shown a statistically significant improvement between preoperative and postoperative knee scores (P < .0001). According to the knee scoring scale, 34 patients (68%) were clinically rated as excellent, 12 (24%) as good, 4 (8%) as fair, with no poor results. All patients have returned to pre-injury jobs (or school), while most resumed some level of sporting activities. No patients complained of patella femoral symptoms postoperatively. Complications included pain over the staple which was used for fixing the ITB to the tibia, requiring removal in 5 patients. These preliminary results are encouraging, with 92% of the patients rating good to excellent. This modified procedure offers advantages over other procedures, as it is entirely arthroscopic with minimal incisions, does not damage the extensor mechanism, and permits an enhanced rehabilitation program.

Radiographic evaluation of native anterior cruciate ligament attachments and graft placement for reconstruction. A cadaveric study

We examined seven cadaveric knees to determine the radiographic location of the native anterior cruciate ligament insertion sites as well as the location of tunnels used in anterior cruciate ligament reconstruction. Posteroanterior and lateral views at several flexion angles were taken with radiopaque markers around the insertions of the native anterior cruciate ligament and subsequent reconstruction tunnels. The femoral insertion was best seen on the 60 degrees notch view. On the lateral view, the femoral tunnel was easily seen as it crossed the roof of the intercondylar notch; however, because of the angle of the tunnel, the actual entrance into the knee may be well distal and anterior to this location. The tibial insertion and tunnel were easily seen at any flexion angle. The center of the insertion was 40% of the tibial diameter from the anterior margin. The lateral view in extension allowed determination of the tibial tunnel's location in relation to the intercondylar notch roof, but by itself did not allow accurate determination of the femoral tunnel's position. Notch and extension lateral radiographs together provided sufficient information for evaluation of anterior cruciate ligament graft position in a convenient, cost-effective format. Neither view by itself provides enough information to evaluate the position of the graft.

A biomechanical comparison between the central one-third patellar tendon and the residual tendon

The purpose of this study was to compare the tensile strength of the central one third patellar tendon--as used for reconstruction of the anterior cruciate ligament--to that of the residual patellar tendon. Ten matched pairs of human cadaveric knees were used for this study, each specimen consisting of an intact patella-patellar tendon-proximal tibial unit. One knee from each pair was randomly selected for removal of both the medial and lateral one third of the patellar tendon, leaving the central one third intact. The contralateral knee of each pair underwent removal of the central one third of the patellar tendon, leaving the residual two thirds intact. Each specimen was then mounted in a materials testing machine and tensile tested to failure at a strain rate of 100%.s-1. The most important result to emerge from these experiments was that there was no significant difference in maximum force to failure for the residual patellar tendon compared to the central one third. Thus any thought that removal of the central one third as a graft still leaves a tendon twice as wide and therefore twice as strong as a graft is dispelled by these experiments.

A new device and method for controlling the load in rabbit medial collateral ligament reconstructions

In order to study the effect of intra-operative tensioning on the laxity and strength of healing ligament grafts in an animal model, a method of quantifying graft tension was needed. In this study a sensitive ligament tensioning device was developed to measure accurately the prefixation loads in the rabbit medial collateral ligament (MCL) graft. To verify that reproducible changes in ligament tension could be created with the tensioning device, a group of animals had their MCL grafts replaced at one of three different graft loads (tight, anatomic, or loose). The tensioning device consists of two posts which move relative to one another by means of an axial screw. The movable post, which is inserted into the tibial bone island of the MCL graft has a series of strain gauges which can measure the tension applied to the graft. The stationary post attaches to the tibial shaft, permitting the ligament graft to be tensioned relative to this fixed point. After graft tensioning and fixation, the animals were euthanized immediately postoperatively and their ligament load-deformation behavior was measured using an Instron materials testing machine. Specific measures of low load behavior was taken to quantify ligament laxity. Our results demonstrate that the tensioning device was capable of reproducibly altering prefixation graft load intra-operatively as well as MCL laxity immediately postoperatively. A baseline of laxity values was thus developed to follow changes in this laxity measure for future studies of MCL graft healing in this model.

Anterior cruciate ligament reconstruction: endoscopic versus two-incision technique

The purpose of this study was to compare the single-incision, "endoscopic" (ENDO) anterior cruciate ligament (ACL) reconstruction technique with the two-incision, "rear-entry" technique (RE). Sixty patients were entered into a prospective study. Thirty patients underwent ACL reconstruction by the RE technique, followed by 30 consecutive patients using the ENDO procedure. Postoperatively all patients followed a standardized rehabilitation protocol. Follow-up evaluation consisted of a detailed physical examination, range of motion, thigh girth, vertical leap, hop test, KT-1000 testing, and patient interview. They were scored according to the International Knee Documentation Committee (IKDC) protocol, which takes objective and subjective data into account. Patients were also assessed for level of sports activity including frequency and type. Finally, anteroposterior and lateral x-ray films were evaluated with a scoring system for tunnel location. Of the initial 60 patients entered into the study, 50 were available for a detailed clinical and functional review (83%). Demographic comparisons revealed 24 RE patients and 26 ENDO patients. There were 16 men and 8 women in the RE group. The ENDO group comprised 16 men and 10 women. There were 14 right knees and 10 left knees in the RE group. In the ENDO group there were 13 right knees and 13 left knees. The average age in the RE group was 24 years and 25 years in the ENDO group. The average follow-up was 35 months (range 31-40 months) in the RE group and 29 months (range 24-35 months) in the ENDO group. Complications included two patients with loss of motion in the RE group and three in the ENDO group. There were no significant differences between the two groups tested with respect to the overall IKDC rating scale. Anteroposterior and lateral x-ray films revealed no significant differences in femoral and tibial tunnel placement. In conclusion, no significant functional or radiographic differences at a minimum 2-year follow-up could be identified when comparing the two ACL reconstructive techniques.

Tibial tunnel placement in ACL reconstruction

In reconstructing the ACL, ideal tibial tunnel placement requires an understanding of the unique anatomy of the ACL tibial footprint and its relationship to the PCL, lateral meniscus, and medial tibial part of the spine. In addition to precise placement of the tibial tunnel, its length and angulation are factors to consider. Using consistent anatomic landmarks with attention to detail, the tibial tunnel can be reproducibly placed in a manner that is not detrimental to the graft.

Biochemical properties of collagen from ligaments and periarticular tendons of the human knee

The biochemical properties of collagens from the periarticular connective tissues of the human knee (ligaments, semitendinosus and gracilis tendons, and the iliotibial band) were investigated in subjects ranging from 20 to 70 years of age. Although the total collagen content of most tissues was more than 90% of the dry weight, the anterior cruciate ligament and the iliotibial band had relatively low collagen contents. There were no significant changes in the tissue collagen content with aging. However, the anterior cruciate ligament and the patellar tendon of the 20-year-old subject had a higher content of soluble collagen than the other ligaments and tendons. The iliotibial band of the 20-year-old subject contained more collagen that was soluble by a combination of salt, sodium citrate extractions and pepsin digestion. Dihydroxylysinonorleucine was the major reducible cross-link of collagen from all the ligaments. The amount of dihydroxylysinonorleucine in the anterior cruciate ligament of the 20-year-old subject was much higher than that in the other ligaments. In contrast, the tendons and the iliotibial band contained a large amount of histidino-hydroxymerodesmosine and hydroxylysinonorleucine, while the patellar tendon was the only tendon with a significant content of dihydroxylysinonorleucine. Hydroxypyridinium non-reducible cross-links were more abundant in collagens from ligaments than in collagens from the other tissues. The cross-link study and the analysis of collagen solubility showed that patellar tendon collagen more closely resembled the collagen from the anterior cruciate ligament than that from periarticular tendons. It was also shown that the anterior cruciate ligament contains relatively immature collagen compared with the other ligaments.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of reconstruction of the anterior cruciate ligament on proprioception of the knee and the heel strike transient

Abnormal proprioception of the knee joint has been documented after rupture of the anterior cruciate ligament (ACL) and may result in the loss of muscular reflexes. Excessive loading from the lack of muscular control may predispose the joint to osteoarthrosis. To investigate this problem, 10 patients were studied at an average of 31.6 months after ACL reconstruction. Three tests of joint proprioception and measurements of the vertical component of heel strike force during normal gait were used. A normal control group also was studied. For two of the proprioception tests (reproduction of passive motion and relative reproduction), there were no statistical differences among the uninjured (control) limbs, the normal contralateral limb of patients with a reconstructed ACL, and the extremity with a reconstructed ACL. In the third test (threshold of detection of motion), which previously has been shown to be adversely affected by ACL injury, the measurements for both extremities of patients with a reconstructed ACL were more accurate than those for the control group. The reconstructed extremity performed less accurately than the contralateral extremity (p < 0.05). The heel strike transient (vertical component of ground reaction force at heel strike) for uninjured and ACL-reconstructed limbs was not significantly different. In fact, the extremity with the reconstructed ACL had a lower transient than the uninjured extremity. Heel strike transients in patients with a reconstructed ACL were higher than those in the controls, but the differences were significant only when corrected for velocity of gait.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of anterior cruciate ligament graft tensioning direction, magnitude, and flexion angle on knee biomechanics

The objective of this study was to determine the biomechanical effect of graft tensioning during reconstruction of the anterior cruciate ligament. We evaluated the magnitude of the tensioning force (22 or 67 N), the flexion angle at which the tension was applied (extension or 30 degrees of flexion), and the direction of application of the tensioning force (proximal, distal, or distal with a posterior force simultaneously applied to the tibia) on 10 fresh cadaveric knees. The anterior cruciate ligament was reconstructed using a bone-patellar tendon-bone graft. The graft was then temporarily fixed during the application of each of 12 combinations of tensioning variables listed above. After each fixation, graft force and joint motion were measured during anterior tibial loads. Tensioning direction and the flexion angle significantly affected graft force and joint motion, while the magnitude of the graft tensioning did not. Graft forces were greater when the tensioning was applied at 30 degrees of flexion. Compared with distal tensioning with and without posterior tibial force, graft forces with proximal tensioning were greater in extension and lower in flexion. The position of the tibia relative to the femur was posterior and externally rotated, compared with normal, for all combinations of tensioning variables in both unloaded and anterior load states.

Reconstruction of the anterior cruciate ligament with Achilles tendon autograft

The increasingly serious complications of artificial ligaments and allografts have brought them into disrepute. Recently, autografts have drawn more attention. A new type of autograft, the Achilles tendon autograft, has been developed and applied to anterior cruciate ligament reconstructions. This report describes the advantages of the Achilles tendon autograft used and presents the results of a prospective study of 21 patients with minimum 2 year follow up. Of the 21 cases, 16 patients (75%) had a rating of excellent; 2 (10%) good, 2 (10%) fair, and 1 (5%) poor. Preoperative knee scores of 56.7 were improved to 89.5 postoperatively. The authors removed less than half of the Achilles tendon with the calcaneal bone incorporated. Through magnetic resonance imaging we confirmed that the remaining Achilles tendon of the donor site regained its volume and strength within a year without significant complication. Achilles tendon autograft offers the advantages of length, elastic strain modulus, reproducibility in technique, and consistency of the result without significant complications.

Radiographic analysis of femoral interference screw placement during ACL reconstruction: endoscopic versus open technique

Fifty patients with anterior cruciate ligament reconstruction using a bone-patellar tendon-bone autograft performed by two techniques were evaluated roentgenographically to compare the position of the femoral interference screws. Group I consisted of 25 patients in whom the screw was placed using a distal lateral femoral incision (the two-incision technique). Group II patients underwent arthroscopically assisted intraarticular placement of the screw. These patients were then evaluated with anterior-posterior (AP) and lateral roentgenograms. We observed that the AP and lateral screw angles were significantly different with the two techniques. In addition, the endoscopic placement of the femoral screw had an associated divergence of the screw relative to the bone plug in nine of 25 patients compared with zero of 25 in the open group. In conclusion, radiographic differences do exist between femoral interference screws placed for fixation of an ACL graft using the open approach and those placed endoscopically. Although the clinical significance of these differences is not known, we raise the question of greater divergence in femoral interference screw placement with the newer intraarticular femoral interference screw placement techniques.

How iliotibial tract injuries of the knee combine with acute anterior cruciate ligament tears to influence abnormal anterior tibial displacement

A knowledge of the patterns of injury to the components of the iliotibial tract allows a clearer interpretation of motion limits testing in patients with abnormal anterior tibial translation of the knee (anterior cruciate ligament-deficient knees). Eighty-two consecutive patients with acute knee injuries were classified as anteromedial-anterolateral rotatory instability (anterior cruciate ligament-deficient) based on the abnormal motion demonstrated by clinical examination tests for instability. At surgery, injuries to the intraarticular and extraarticular anatomic structures were identified and correlated to the abnormal grades of motion demonstrated by the knee motion limits examination. Tears of the anterior cruciate ligament occurred in 80 (98%) of the knees. However, the grade of abnormal motion demonstrated by the Lachman and pivot shift tests was quite variable. This variation did not correlate statistically with anterior cruciate ligament tears. Injuries to the anatomic components of the iliotibial tract were confirmed in 76 (93%) of the knees. These injuries correlated highly with variations in grades of abnormal motion detected by the following tests: lateral joint line opening at 30 degrees (r2 = 0.05); Lachman test (r2 = 0.08); pivot shift (r2 = 0.16); and anterior translation at 90 degrees of flexion (r2 = 0.34). Thus, injuries to the components of the iliotibial tract are thought to contribute to the variation in grades of abnormal motion observed in this complex subgroup of anterior tibial translation instabilities.

Proprioception Following Anterior Cruciate Ligament Reconstruction

Injury to the anterior cruciate ligament (ACL) is thought to disrupt joint afferent sensation and result in proprioceptive deficits. This investigation examined proprioception following ACL reconstruction. Using a proprioceptive testing device designed for this study, kinesthetic awareness was assessed by measuring the threshold to detect passive motion in 12 active patients, who were 11 to 26 months post-ACL reconstruction, using arthroscopic patellar tendon autograft (n=6) or allograft (n=6) techniques. Results revealed significantly decreased kinesthetic awareness in the ACL reconstructed knee versus the uninvolved knee at the near-terminal range of motion and enhanced kinesthetic awareness in the ACL reconstructed knee with the use of a neoprene orthotic. Kinesthesia was enhanced in the near-terminal range of motion for both the ACL reconstructed knee and the contralateral uninvolved knee. No significant between-group differences were observed with autograft and allograft techniques.

The effect of tibial attachment site on graft impingement in an anterior cruciate ligament reconstruction

Anterior cruciate ligament reconstructions were performed in 14 cadaveric knee specimens using a 6-mm wide polypropylene graft. The graft was passed through a femoral tunnel at the attachment site of the anterior medial bundle of the anterior cruciate ligament. Seven tibial positions were evaluated as to the change in attachment site distance with passive range of motion and impingement on the intercondylar notch as the knee was passively ranged from 0 degree to 90 degrees of flexion. Impingement was also evaluated while the knee was extended by pulling through the quadriceps tendon. The tibial placement site affects the change in attachment site distance with passive range of motion and impingement on the intercondylar notch. Grafts passed through drill holes anterior and lateral to the insertion of the anterior fibers of the anterior cruciate ligament consistently produced impingement on the anterior outlet of the intercondylar notch. Knee extension with quadriceps tendon pull produced graft impingement in a greater arc of flexion than passive extension. Based on this study, optimum placement of the tibial hole should be at the insertion of the anterior medial fibers of the anterior cruciate ligament. Impingement recognized during surgery can be alleviated with notchplasty. With passive extension there should be a 3-mm clearance between the anterior portion of the intercondylar notch and the ligament graft to prevent the graft from impinging when the knee is actively extended.

The results of fresh-frozen patellar tendon allografts for chronic anterior cruciate ligament deficiency of the knee

This prospective study was done to evaluate the clinical outcome of fresh-frozen patellar bone-tendon-bone allograft tissue used as a substitute for chronic insufficiency of the anterior cruciate ligament. Forty-one patients were followed at a mean of 27 months after surgery. The mean time from injury to reconstruction was 34 months. The same operative procedure and postoperative rehabilitation was performed on each patient. The evaluation method consisted of subjective, objective, and instrumented laxity testing. Thirty-seven patients (90%) thought their knee was normal or improved after surgery and had no further episodes of giving way. The combined modified Hughston Knee Score revealed 30 patients (73%) with an excellent or good result and 9 patients (22%) with a fair or poor result. The mean postoperative Lysholm Knee Score was 91 (range, 56 to 100). Thirty-two had a negative pivot shift (78%). The postoperative KT-1000 arthrometer revealed 37 patients had an injured-to-uninjured difference of 5 mm or less (mean, 1.32 mm; range, 0 to 5). There were three traumatic failures at 24 months postoperatively in this group. There was no rejection phenomenon noted postoperatively. In addition, clinical observation showed less postoperative morbidity when compared to a matched autogenous patellar tendon control group.

Physiopathology of the knee joint after distal iliotibial band transfer

In an experimental study of 14 cadaver knee joints, the pressure load on the joint surface after distal iliotibial band transfer was measured using Fuji Prescale foils. With an intact anterior cruciate ligament, increases of up to 153% for the average pressure load and of 225% for the total pressure in the lateral compartment were found in relation to the fixation point chosen. At point P3--slightly dorsal to the insertion of the lateral collateral ligament--the area loaded with maximum pressure increased to six-fold. Fixation at the transition of the lateral femoral condyle to the femoral shaft at the start of the linea aspera was associated with the least pressure increases in both the lateral and the medial compartments. Under all experimental conditions, lateral extra-articular stabilization with fixation at the insertion of the fibular collateral ligament was shown to be associated with significantly higher load increases. While a shift of pressure load to the dorsal third was seen in the lateral compartment, the mid-third remained the focus of the pressure load in the medial compartment. After transection of the anterior cruciate ligament and iliotibial band transfer at the "over-the-top" point, a significant shift of pressure towards the medial compartment was seen, while the lateral pressure load decreased. Medially, the area loaded with peak pressure remained constant, while the corresponding area in the lateral joint space showed a highly significant decrease to nearly one-third of normal. After additional bilateral meniscectomy this tendency was even more pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)

Pes anserinus and iliotibial band transfer for anterior cruciate insufficiency

Twenty-one patients with chronic anterior cruciate ligament insufficiency were treated with a combined iliotibial band (Ellison) and pes anserinus (Slocum-Larson) transfer procedure. Preoperatively, the most prominent instabilities were drawer laxity in 16 patients and anteromedial rotation in 5 patients. After a median of 34 months of followup, 15 patients were absolutely satisfied with the result, 2 were fairly satisfied, and 4 were not satisfied at all, including 2 patients who had been reoperated. All of the patients with unsatifactory results had a pivot shift and a positive Slocum test. Intraarticular derangements had no influence on the results. At followup, 14 patients demonstrated an anteromedial rotatory instability, indicating that the lateral stabilization procedure acted better than the medial one. Only a few patients returned to their preinjury levels of sports activity. Compared with other extraarticular procedures in the literature, the results were quite similar. The operative procedures used in this study cannot be recommended in cases with combined instabilities of the knee.

The effects of graft tensioning on the laxity and kinematics of the anterior cruciate ligament reconstructed knee

An in vitro study of eight cadaveric knees was conducted to investigate the effect of initial graft tension on the laxity and full three-dimensional kinematics of the anterior cruciate ligament reconstructed knee. A parallel strand, prototype, expanded polytetrafluoroethylene graft (W. L. Gore and Associates, Flagstaff, AZ, U.S.A.) was used. The graft was placed in the over-the-top position with initial tensions of 18, 36, 54, 72, and 90 N applied with the knee in full extension or at 30 degrees of flexion. The motion of the tibia relative to the femur was measured by a 6 degrees-of-freedom spatial linkage, and the applied forces and moments, the quadriceps force, and the graft tension were measured by load cells. Near normal anterior laxity in the Lachman test was restored with all the tested initial graft tensions. However, over constraint, posterior, lateral, and external tibial subluxation, and abnormalities in joint stiffness developed as the initial graft tension increased. Graft tension-related posterior tibial subluxation resulted in an increase in quadriceps force needed to achieve full extension.

Anterior cruciate ligament reconstruction using freeze-dried, ethylene oxide-sterilized, bone-patellar tendon-bone allografts. Two year results in thirty-six patients

Thirty-six of 44 patients (82%) who underwent ACL reconstruction using freeze-dried, ethylene oxide-sterilized, bone-patellar tendon-bone allografts were evaluated at least 2 years postoperatively. A detailed subjective evaluation using the Lysholm scale was recorded as well as a functional evaluation using the Tegner activity scale. All of the patients received a detailed physical examination that included testing with the KT-1000 ligament arthrometer and the Cybex dynamometer. Complete chart reviews and radiographic evaluations were also obtained. Only 17 patients were considered to be functionally successful and performing at their desired activity level. The average KT-1000 showed a side-to-side difference of 5.9 mm at 30 pounds for the successful group and 7.9 mm for those who had functional failure. The Lysholm scores were 91.6/100 versus 61.1/100 in the failures. Eight patients (22%) at repeat surgery were noted to have complete dissolution of the graft. Large femoral cysts were noted radiographically in all of these patients. It was concluded that freeze-dried, ethylene oxide-sterilized, bone-patellar tendon-bone allografts have a high failure rate and cannot be recommended for ACL reconstruction.

Anterior cruciate ligament replacements: a mechanical study of femoral attachment location, flexion angle at tensioning, and initial tension

We examined three surgical variables that affect the ability of an anterior cruciate ligament replacement to restore the limit of anterior tibial translation. These were the placement site of the substitute on the femur, the initial tension applied to the replacement, and the flexion angle of the knee at the time of tensioning. An anterior load of 100 N was applied to the tibia. As the knee was flexed, we measured the tensile force in the substitute and the anteroposterior position of the femur relative to the tibia. Placement largely determined whether the force in the replacement increased or decreased with flexion. Placement also largely determined whether the tibia moved anteriorly or posteriorly with flexion compared to its position in the intact knee. The initial tension and the flexion angle at tensioning affected the magnitude of force in the substitute and the magnitude of the change in AP position. They did not affect how force and AP position changed with flexion. Greater increases in force and greater posterior shifts in tibial position were produced by changing the flexion angle at tensioning from 0 degrees to 30 degrees than by increasing the initial tension from 22 to 44 N.

Clinical comparison of freeze-dried and fresh frozen patellar tendon allografts for anterior cruciate ligament reconstruction of the knee

The aim of this study was to evaluate the clinical outcome of freeze-dried compared to fresh frozen allograft tissue used as a substitute for a ruptured ACL of the knee. In addition, the incidence of any graft rejection phenomena was recorded. Forty-one patients with ACL deficient knees underwent reconstructive surgery using a patellar bone-tendon-bone allograft that had been freeze-dried (Group 1, N = 14) or fresh frozen (Group 2, N = 27). All patients underwent the same implant technique and rehabilitation program. Followup ranged from 24 to 36 months. The evaluation consisted of subjective, objective, and instrumented laxity testing (KT-1000, MEDmetric, San Diego, CA; and Genucom, FARO Medical Technologies, Inc., Montreal, Canada). There were 31 males and 10 females. Eleven (79%) patients in Group 1 thought their knee was "normal" or "improved," and 25 (93%) in Group 2 thought the same. In addition, 10 (71%) patients in Group 1 denied any "giving way," compared to 26 (96%) in Group 2. The mean Lysholm knee score in Group 1 was 86/100 (range, 22 to 100) compared to 92/100 (range, 59 to 100). Clinical examination included the Lachman test and tests for anterior drawer sign and pivot shift. Postoperatively, Group 1 patients had the following results: Lachman test--seven Grade 0, six Grade 1, one Grade 2; anterior drawer sign--eight Grade 0, five Grade 1, one Grade 2; and pivot shift--seven Grade 0, five "trace," and two "present."(ABSTRACT TRUNCATED AT 250 WORDS)

The anterior cruciate ligament

Our knowledge of the anterior cruciate ligament has expanded rapidly over the last decade. Recent advances in arthroscopic techniques, the development and release of synthetic stents and prostheses, increasing laboratory and clinical data involving allograft implantation, and biomechanical research in knee rehabilitation have led to a bewildering array of choices for treatment of anterior cruciate ligament deficiency. As new information and techniques are presented, and new synthetic and biological materials become available, orthopedic surgeons must judge their value and modify treatment recommendations accordingly. A thorough knowledge of the basic science and clinical information is necessary to appropriately evaluate these new advances. A review of our current knowledge of the anterior cruciate ligament is presented to facilitate this evaluation process.